1. Field of the Invention
The present invention relates to a head-protecting airbag apparatus mounted on an upper periphery of a window of vehicle and including an airbag that is mounted to the vehicle body structure by an upper edge thereof and deployable downward by inflation gas to cover the window.
2. Description of Related Art
In the prior art, JP 2001-328503 is illustrative of a head-protecting airbag apparatus mounted on an upper periphery of a window of a vehicle. This apparatus includes an airbag that extends up to below the beltline of a door at deployment so as to properly protect an occupant's head in the event of rollover. Specifically, the airbag of this conventional airbag apparatus includes a head-protecting portion that has a plurality of vertical cells inflated in rod-shape and disposed side by side along an anteroposterior direction at deployment, and an extended inflatable portion below the head-protecting portion. The extended inflatable portion is thinner than the head protecting portion and extends up to below the beltline at deployment.
In the event of rollover, by way of example, however, if an occupant's head, which is moving outward, contacts a boundary between the vertical cells of the above conventional airbag, the head-protection portion is likely to bend in V-shape as viewed from above due to the pressure applied by the occupant's head. At this time, although the extended inflatable portion is inflated and located on the inboard side of the beltline of a vehicle door, due to its thinness, it is possible for the extended inflatable potion to bend in a V-shape as well, overpass the belt line and eventually eject from the vehicle. Therefore, it is desired to securely retain an occupant's head within the vehicle during rollover for proper protection of the occupant's head.